Aegilops; phylogeography; genome dynamics; wheat; phylogeny; hybrid zone; next generation sequencing; transposable elements
Prinzing Andreas, Ozinga Wim A., Brändle Martin, Courty Pierre‐Emmanuel, Hennion Françoise, Labandeira Conrad, Parisod Christian, Pihain Mickael, Bartish Igor V. (2017), Benefits from living together? Clades whose species use similar habitats decline less., in New Phytologist
, 213(1), 66-82.
Lafon-Placette C Vallejo-Marín M Parisod C Abbott RJ Köhler C (2016), Current plant speciation research: unraveling the processes and mechanisms behind the evolution of reproductive isolation barriers., in New Phytologist
, 209, 29-33.
Senerchia N Felber F North B Sarr A Guadagnuolo R Parisod C (2016), Differential introgression and reorganization of retrotransposons in hybrid zones between wild wheats, in Molecular Ecology
, 25(11), 2518-2528.
Parisod C Broennimann O (2016), Towards unified hypotheses of the impact of polyploidy on ecological niches, in New Phytol
, 212, 540-542.
Senerchia N Felber F Parisod C (2015), Genome reorganization in F1 hybrids uncovers the role of retrotransposons in reproductive isolation, in Proceedings of the Royal Society of London. Series B
, 282(1804), 20142874.
Background: Transposable Elements (TEs) represent a major fraction of genomes, but to what extent the TE content influences and is influenced by the evolutionary trajectories of host genomes remains poorly known. Environmental stresses, hybridization and polyploidy have been shown to induce TE proliferation, but data on variation of TE fractions across species ranges is limited. Recent findings show that wheat and wild Aegilops relatives underwent drastic genome reorganization in association with allopolyploidy and TE dynamics, suggesting that TEs are central to their diversification. General objectives: Empirical population genetics of TE dynamics addressing the processes acting on closely related host taxa is necessary to disentangle the factors driving the distribution of TEs. The present proposal focuses on a set of 4 diploid Aegilops and 4 derived allopolyploid species (i.e. MCDU cluster). Based on our expertise of these species and their active TEs, we aim to determine to what extent genomes and TEs evolved independently. Inference and dating of the divergence between diploids and of the origin(s) of polyploids will provide a robust framework to assess the comparative phylogeography of their genome and TE fractions. Of particular interest will be the comparison of central vs. marginal spontaneous hybrid zones to test for the factors affecting TE genome content.Experimental design and approaches: The proposal aims to address three complementary questions:(1) What are the respective patterns of speciation in diploid and derivative polyploid species of the MCDU cluster of Aegilops? A dated phylogeny of species of the MCDU cluster will be inferred based on a multilocus survey and will give a clear understanding on its evolution.(2) Are the spatiotemporal trajectories of genomes and TEs independent? A large phylogeographic survey of the eight species over the Mediterranean area will compare genetic data based on SSAP (i.e tracking TE insertions) and AFLP (i.e. random sequences). It will highlight areas of particular TE dynamics and TE evolutionary trajectories across the species ranges. (3) Are evolutionary forces acting on the accumulation of TE insertions different in central vs. marginal populations? Fine-scale investigation of corresponding hybrid zones in the central vs. marginal part of their range will test the dynamics of TEs and the processes shaping the distribution of TE insertions on the long term. Experimental F1 hybrids between Aegilops polyploids (i.e. Ae. geniculata and Ae. triuncialis) will quantify the short-term dynamics of TEs in response to hybridization.Significance of the project: Comparing evolutionary trajectories in space and time of related species and their inhabiting TEs has so far not been investigated. Aegilops spp. offer a unique opportunity to examine factors underlying the distribution of TEs within and among species. In particular, this project tests the respective influences of genetic differentiation (central vs. marginal populations), hybridization (experimental and natural pure vs. hybrid populations) and polyploidy (diploids vs. allopolyploid) on TE genome contents. Addressing such questions at complementary spatial scales will offer original insights on the evolutionary forces controlling TE dynamics in natural populations. Evolutionary processes shaping TE variation share analogies with traditional host-parasite systems, but it remains unclear to what extent such co-evolutionary relationships adequately describe genome-TE systems. Data gathered here on complex Aegilops genomes will be crucial to evaluate theoretical advances required to understand the evolution of genome architectures. It will thus be of interest to evolutionary and molecular biologists as well as ecologists.